Method of coating yarn



United States Patent Ofiice Patented Jan. 17, 1967 3,298,854 METHQD FCOATING YARN Alfred Marzocchi, Cumberland, and Adrien E. Beaudoin,

Central Falls, ILL, assignors to Owens-Corning Fiberglas Corporation, acorporation of Delaware No Drawing. Filed Feb. 2, 1962, Ser. No. 170,8179 Claims. (Cl. 117-72) The present invention relates to an improved yarnof the glass fiber type and to a method of producing the improved coatedyarn. A yarn formed of fiber glass, of course, is composed of aplurality, usually several hundred, individual filaments which have beendrawn from a forming bushing, subsequently cooled to harden them andthereafter combined with like formed strands by twisting, usinggenerally several strands to form the ultimate composite yarn. It isconventional, of course, to treat the individual filaments and similarlyit has been general practice to coat the ultimate yarn with a resin,usually a vinyl resin, to form a composite vinyl-yarn product. Thecoated yarns may thereafter be woven to form fabrics of various weaveconstructions selected in accordance with the particular end use towhich the Woven fabric will be put, e.g. yard goods, drapery material,etc. Some of the coated yarns are not close woven but are combined in anopen type weave construction to yield a definitely perforate,screen-like material which is adapted to be mounted in a frame and usedfor window screening and the like.

Coatings for yarns of glass fiber and the like which are to be used inthe last mentioned application have evidenced and demonstrated someshortcomings and drawbacks in the application thereof to the yarn and inthe preparation of the screen. Thus, some yarn coatings have been foundto be subject to flattening at the point of juncture of crossing yarns,e.g. those at right angles. This indicates that the coating is too softand while a slight weld between the crossing coated yarns is desirableit is not desirable for the coated yarn to become flattened since thisleads to a weakening and ultimate breaking of the screen. Most desirablythe yarn should retain the cross sectional shape in which it is finallyformed in the coating operation. This cross section is usually circularwith the individual filaments or strands in uniform relationship to eachother and embedded'in more or less of a matrix of the coating material.

It also has been found that the coatings usually formed of a vinyl resin(utilizing a vinyl plastisol technique) are not resistant to exposure tothe normal temperature and atmospheric conditions. It has been suspectedthat the deficiency of the coatings used heretofore is due to the factthat the plasticizer component of the vinyl plastisol bleeds from theyarn, leaving a somewhat rigid or stiffened vinyl resin. The more rigidor stiffened vinyl matrix, of course, cannot endure any type of flexwithout having cracking induced therein leading to the ultimatedestruction of the yarn or of the screen composed thereof.

Furthermore, the vinyl plastisol technique is quite slow, necessitatingparticular time/temperature relationships to effect fusion of the vinylchloride without any heat degradation.

It is the object of the present invention to provide a novel method ofcoating yarn of fiber glass or the like which method overcomes theabove-noted deficiencies.

It is another object of the present invention to provide a method whichmay be carried out very expeditiously and simply without serious orextensive modification of existing apparatus and assembly line setups.

It is still another object of the present invention to provide a coatedyarn of fiber glass or the like which coated yarn is more flexible andweather resistant than yarns known heretofore in the art.

It is yet another object of the present invention to provide a method ofthe character described which method is flexible in that several stepscan be interchanged and adjusted to meet the particular requirements ofthe ultimate yarn.

It is another object of the present invention to provide a coated yarnin which the coating composed predominately of a vinyl resin is moreefficiently and completely bonded to the fiber glass elements making upthe yarn.

It is still another object of the present invention to provide a methodof coating a yarn formed of glass fiber or the like which method permitsthe coating operation to be carried out at a speed greater than knownheretofore and without any higher temperature being employed.

It is another object of the present invention to provide a method asjust described which, at the same time, permits the production of acoated yarn which is more flexible, stronger and resistant todeleterious influences than heretofore known.

It is likewise an object of the present invention to provide a yarn ofglass fibers or the like bearing a metallic reflective and conductivecoating.

It is also an object to provide a method for producing a yarn bearing acoating which is reflective and conductive.

The above, as well as other objects of the present invention, willbecome apparent to those skilled in the art from the following detaileddescription of the invention together with specified recitation ofexamples of the specific and the best mode of carrying out the processof the invention to yield the novel and improved coated yarn of glassfibers or the like.

In its simplest embodiment the present invention contemplates theplacing of several distinct coatings onto the yarn followed by thesubjection of the coated fiber to a hot air oven to set the coatings.One of the coatings applied to the yarn constitutes an intimate physicalmiX- ture of a fusible vinyl plastisol and a polymerizable materialwhich is either a substance containing epoxy functionality or asubstance containing active isocyanato active groups. The other coatingcomprises a relatively low boiling substance which is capable ofcatalyzing the polymerization of the epoxy containing substance or theisocyanato group containing substance. As indicated, the coated yarn issubsequently exposed to an environment which will cause the low boilingsubstance to migrate into the other coating and initiate thepolymerization or cross linking of the epoxy or isocyanato groupcontaining substance. The condition should also, of course, effectsimultaneous fusion or gelation of the vinyl plastisol. Vinyl plastisolmaterials are, of course, well known in the art as constituting a massof vinyl chloride polymer particles suspended in a matrix formed usuallyof a plasticizer. The plastisol is a fairly viscous liquid which, whenheated, causes the plasticizer usually a phthalate ester or asubstituted phthalate ester to permeate the vinyl chloride particle andswell it. As it swells and the temperature is elevated, a fused orgelled product is formed which is either rigid or relatively soft andflexible depending upon the proportion of plasticizer which has beencombined with the vinyl chloride powder or particles. In accordance withone aspect of the present invention we modify the vinyl plastisols knownheretofore, and as briefly described hereinabove, by including thereinanother polymerizable substance. One of the polymerizable substanceswhich we incorporate as a modifying ingredient is an epoxy resin. Theseare known conventionally in the trade as epoxides. The epoxides aregenerally hydrocarbon in nature and contain attached thereto, as apredominant functional group, the radical The epoxide, diepoxide orpolyepoxide (containing one or more groups) may be a relatively simplemonomer or it may be derived from a somewhat longer chain complex esteror carboxylic acid having a portion of the ester or carbocyclic acidfunction replaced by the epoxy group or the epoxide radical. The epoxygroup polymerizes by a breaking or schism of one of the carbon oxygenbonds leading to the formation of ether linkages in the polymerizate.Also epoxy groups may cross link with epoxy groups in an adjacent chain.Most preferably, the epoxide for use in the present invention should bean epoxide which has a degree of flexibility already built into thebackbone of the polymer. An example of such an epoxide is ethyleneglycol diepoxide having the structural formula:

where x varies from 2 to about 10. Another group of compounds havinginherent flexibility is the modified triglycerides. Such materials areillustrated, for example, by epoxidized soybean oil or epoxidized talloil. In such cases oxidation of the C non-conjugated olefinic fatty acidyields the epoxidized ester. The epoxy group may also be present on thebenzene ring portion of a phthalate ester in which the ester portion isa long chain fatty acid derivative.

The epoxide is combined with the vinyl plastisol by simply mixing thetwo ingredients together with a conventional plasticizer such as one ormore of the alkyl substituted phosphates or one or more of alkylsubstituted phthalate esters, or mixtures thereof. The epoxide and theconventional vinyl plasticizer should be combined in such amounts as toconstitute a total of from about 35 to about 65 parts of these twocomponents per 100 parts of dry vinyl chloride. Preferably the vinylplastisol, as so modified ready to be applied to the yarn, should have aviscosity between about 2,000 centipoises and about 10,000 centipoises.A plastisol within this range is quite practicably workable, insuringefficient and uniform distribution of the epoxide throughout theplastisol and at the same time providing effective coating of the yarntogether with impregnation of the free spaces or interstitial voidsbetween the plurality of filaments.

The fusible vinyl chloride plastisol may also be modified, in accordancewith the invention, by including therein, to form an intimate physicalmixture, an amount of a substance containing reactive isocyanato groupsor a substance which is capable of yielding isocyanato reactive groupsunder the conditions of the coating or under the oven drying conditionssubsequent thereto. Materials containing active isocyanato groups are,for example, the organic diisocyanates including ethylene diisocyanate;

. trimethylene diisocyanate; tetramethylene diisocyanate;

hexamethylene diisocyanate; decamethylene diisocyanate; m-phenylenediisocyanate, pcp -diphenyl diisocyanate, naphthalene diisocyanate andlike compounds. When the added ingredient is an isocyanate ordiisocyanate having active NCO groups, there should, preferably, beincluded a copolymerizing substance having re active hydrogen groupssuch as a polyester or a polyether glycol. It is not always necessary,of course, to use a copolymerizing substance since the diisocyanateswill copolymerize in and of themselves. Frequently, it is desirable touse an isocyanate which has been previously reacted to form an adductthereof. Thus, particularly in the case of diisocyanates, an adduct ofthe diisocyanate with a hydroxyl bearing aryl, alkylaryl, aralkyl orlike compound is desirable since the aryl radical blocks the reactivityof the isocyanato group. A mixture of vinyl plastisol and an adduct of,for example, ethylene diisocyanate and phenol possesses improved shelflife. The adduct of phenol will be found, upon exposure to the elevatedtemperature in the drying oven as described hereinafter, to have givenup the phenol group revealing the reactive isocyanato group for rapidpolymerizing at the desired time.

Preferably, in accordance with this invention the presence of water inthe plastisol or during the coating operation should be avoided sincethe NCO of the isocyanate tends to react preferentially therewithreducing the copolymerization of the NCO with the hydroxyl containingpolyester, polyalkylene ether glycol or the like and thereby detractingfrom hardness, toughness and the like. In combining the isocyanate andthe reactive hydrogen containing compound with the vinyl plastisol, theisocyanate should be present in sufficient amount that there are presenttherein an excess of NCO groups in order that in the final oven curingstep the isocyanate may react with the urea or urethane groups toprovide a branching of the intermediate linear chains or the crosslinking of already formed branch chains. The polyester adducts are knownin the art and no detailed description need be given beyond stating thatthey are formed from the condensation products of dicarboxylic acids anddihydric alcohols. The polyalkylene ether glycols are also known in theart to constitute condensation products of alkylene oxides capped, forexample, at a terminal stage of the reaction with, for example ethyleneoxide to stop the reaction and prevent it from continuing to anundesirable high molecular weight.

The polyalkylene glycols or ether glycols may also be condensed withpolyhydroxy materials to yield more reactive substances for formingvarious adducts with the isocyanate or polyisocyanate. The use of thepolyhydric materials such as pentaerythritol (containing a largeproportion of primary hydroxyl groups) tends to result in a greateramount of hardening of the ultimate isocyanate or a urethane reactionproduct concurrent with the fusion of the vinyl plastisol.

The combination or modification of the vinyl plastisol with theisocyanato group containing substance, or adduct of said isocyanatosubstance, should follow the same general procedure as set forthhereinabove in the description of the combination of the vinyl plastisoland the epoxide additive. That is, the combination will usually includean amount of a conventional ester type plasticizer. The relative amountof the isocyanato or isocyanato adduct and the conventional vinylplasticizer should be selected as to constitute a total of from about 35parts to about 65 parts of these two components per parts of dry vinylchloride, calculated on a dry basis.

It has been found that the isocyanato group containing substance oradduct with the reactive hydrogen containing compound does not functionas a plasticizer to the extent that the epoxide modifier does.Accordingly, in the case of the latter, the epoxide may constitute themajor proportion of the plasticizer, e.g. as much as 45 parts epoxide to20 parts vinyl plasticizer (total being 65) to 100 parts of vinylchloride. In the case of the isocyanato group containing substance theconventional plasticizer should be at least equal to the amount thereof,e.g. about 32 parts of isocyanato group containing substance to 32 partsplasticizer to 100 parts of vinyl chloride. This is particularly true inthe case of the use of the polyurethane adduct of the diisocyanate and apolyether glycol containing an appreciable proportion of primary hydroxycontaining monomers such as pentaerythritol, trimethyol propane or thelike. On the other hand, with the more flexible polyurethanes containingless of the polyhydroxy monomers the amount of the urethane may begreater, approaching 40-50 parts per 100 parts of the vinyl chloride. Inany event, the amount of the urethane or isocyanato group containingsubstance should not be such as to affect materially the viscosity ofthe vinyl plastisol since the viscosity must be such that it can beexpeditiously applied to the yarn of glass fibers and the like and, atthe same time, urged into the interstices, spaces or voids between theindividual filaments making up the yarn.

. The other coating for the production of yarn in accordance with thepresent invention is composed, for example, of a catalyst capable ofpolymerizing the additive added to the vinyl plastisol. The coating maybe formed of a dispersion of the catalyst per se in a vinyl plastisol orin a suitable carrier. Broadly speaking, the catalyst should be onewhich is capable of catalyzing the epoxy polymerization and may be alsocapable of initiating the epoxy ingredient or capable of polymerizingthe NCO or isocyanato group containing substance. A catalyst for one, ofcourse, is not always a catalyst for the other. Accordingly, theinvention contemplates the employment of catalyst for the epoxy groupwhere the epoxies are utilized as the additive for the vinyl plastisoland it envisions the employment in one coating of a catalyst of theisocyanato group, an isocyanato adduct or urethane where the latter isemployed as the additive for the vinyl plastisol.

Amines including primary, secondary and tertiary amines and diaminesrepresent one group of organic catalysts which are capable of catalyzingboth the epoxy polymerization and the polymerization. of compoundscontaining active or free NCO groups. The tertiary amines, of course,are particularly effective catalysts of the polymerization or crosslinking of NCO containing compounds. Examples of amines arediimethylaniline permethylated diethylene triamine, and triethylenetetramine, hexahydrodimethyl aniline, alkyl morpholines, etc. Thealiphatic diamines are in general more reactive than the aromaticdiamines. Furthermore, they have lower boiling points and are therefore.preferred. Examples are: diamino propyl diethylene triamine;triethylamine; trifurfurylamine; diethylene triamine; polyethyleneglycol diamine; diisopropylamine; diisobutylamine; tripropylamine;2-ethyl butyl amine; 2,2-dimethyl butyl amine; symmetrical triazine;alkyl and/ or aryl substituted piperazine, the latter compoundpiperazine having the formula:

and the like. The gaseous amines on the other hand, that is those havingboiling points below room temperature, are not desirable since they arenot retained in the vinyl plastisol but rather escape before they can beeffectively coated onto the yarn or overcoated with the second coatingof vinyl plastisol followed by an introduction into the curing oven. Onthe other hand, even the gaseous amines can be used if they are oneswhich are soluble in the plastisol or in any solvent or other ingredientincluded with the vinyl plastisol.

Carbamic acid esters are also catalysts for the isocyanato group. Theseare obtained by reacting an aliphatic or aromatic or a monohydroxy orpolyhydroxy compound with a monoisocyanate. The hydroxy compound may bemethyl, or ethyl, or propyl or butyl or higher aliphatic alcohol orcyclohexanol. In addition, benzyl alcohol and substituted productsthereofphenols, cresols, and xylenols or substitution products thereof,N,N-dia1kyl-amino-ethanols, glycols such as ethelene glycol,1,4-butylene glycol, diethelene glycol, butene diol, triethanolamine,trimethylolpropane, glycerine and the like are useful in forming thecarbamic acid ester.

Most of the hydroxy containing or active hydrogen containing compoundsare useful as catalysts for the epoxy or epoxide compounds. Thus, thesimple organic amines, diamines and triamines, the dihydric andpolyhydric alco hols and/or even water itself may be used to catalyzethe epoxide reaction and thus may be included or formed as the coatingon the yarn either alone or in admixture with -a plastisol of polyvinylchloride.

In accordance with this invention the catalyst constituting the onecoating, or contained in one of the coat ings, in accordance with thepresent invention should most preferably and ideally have a boilingpoint which is below the temperature maintained in the curing oven.Thus, the catalyst in accordance with the preferred embodiment of theinvention should have a vaporizing or volatilization temperature ofbelow about '450 F. (233 C.). Most ideally, in order to assure thegreatest amount of migration of the catalyst entity into the othercoating containing the vinyl plastisol and eithen the epoxide resin orthe isocyanato, isocyanato group containing compound or urethane, theboiling point of the catalyst contained in the catalyst coating shouldhave a boiling point below about 350 F. (176.7 C.). We have found thatcatalyst having boiling points below these values can be most readilydiffused from one coating to another coating under the conditions ofcoating and drying, as more particularly described hereinafter.

We may also use amine substituted compounds as catalysts forincorporation into coatings in accordance with the present invention. Itis most desirable if the amine substituted compound possesses theability to tie in with or protect the glass yarn surface. One such groupof compounds have the general formula: Y Si(OR) where R is a lower alkylgroup, Y is an amine and a and b are positive numbers whose sum is 4.Tri-ethoxy-aminopropyl silane is a compound of this group which isrelatively stable and may be deposited on the yarn composed of the glassfibers or the like in several forms. It may be deposited in its pureliquid form. It may be deposited from an alcohol, aromatic solvent orother suitable solvent solution. It may be also deposited in the form ofits hydrolysis product which may be, and probably is, somewhatcondensed.

In any event, on the glass it exhibits hydrophobic character preventingor reducing any damage to the glass surface by water, moisture, or thelike. At the same time, the epoxide additive in the vinyl plastisol willbe catalized by the amino group of the silane serving to cross link theepoxide to provide an improved coating, as more par-ticu larly describedhereinafter.

From the foregoing it can be seen that the invention contemplates thepreparation of two coating materials. One is an intimate mixture of avinyl plastisol and either (1) an epoxy or epoxide or (2) an isocyanatogroup containing compound or an isocyanate adduct which is ca-' pable ofbeing converted to a free NCO group and thence undergoing cross linkingpolymerization. The other coating composition is or contains a catalystfor one or the other, or both, of the resinous additives to the vinylplastisol in the coating just previously described. The catalyst coatingmay be the catalyst per se or it may be carried in a suitable diluent orcarrier. In some cases the diluent or carrier may be an alcohol or anaromatic solvent, such as xylene, toluene or the like. In addition tobeing capable of catalyzing the epoxide or NCO-containing additive tothe vinyl plastisol, the catalyst must be relatively low boiling andalso, preferably, it should be soluble or diffusible into the coatingcomposed of the vinyl plastisol and the additive, e.g. the epoxide.

The coatings may be applied to the yarn in any sequence. Thus, thecatalyst or catalyst containing coating may be applied first, followedby the application of the coating composed of the vinyl plastisol andresinous additive. Conversely, the coating of the vinyl plastisol andresinous additive may be applied first, followed by the application ofthe catalyst or catalyst containing coating. The latter, in addition, ofcourse, to being applied per se or in a carrier or diluent, may .beformed in or supplied in the vinyl plastisol. In such cases, it is asimple matter to adjust the amount of vinyl plastisol in the severalcoatings to provide the amount desired, as in the case where the vinylplastisol is present in just one of the coatings. Where the catalyst orcatalyst containing coating is to be applied first, it is sometimesdesirable to preheat the yarn of glass fiber in order to provide anintial driving force for the catalyst migration into the subsequentlyapplied coating of vinyl plastisol and resinous additive.

It is frequently most desirable to carry out the sequence of coatingssuch that the catalyst or catalyst containing coating is applied first,followed by the coating of plastisol containing the resinous additive(the epoxide, isocyanato group containing compound or adduct capable ofundergoing cross linking polymerization). Such a sequence providespolymerization from a point nearest the glass surface proceedingtherefrom outwardly, as it were. This avoids and/or reduces theformation of any blistering, such as may occur in a rigorous crosslinking reaction of the resinous additive. Furthermore, it avoids and/or reduces the formation of any skin on the outer surface of the coatedyarn.

In accordance with another aspect of the present invention, the amountof catalyst may be selected so as to be insufficient to causepolymerization of all of the epoxide, s,

The advantage of this procedure is that the resulting final plastisolcoating will be inherently stable against heat degradation, such thatexposure to heat will first complete polymerization before being able toexert any heat degradation influence on the plastisol coating.

The coatings are applied conventionally, that is, the coatings areapplied by simply allowing a stream of the liquid catalyst or viscousresin to flow onto the laterally moving yarn. The yarn immediately moveslaterally through a wiping die which has an orifice which is flaredslightly to meet the incoming strand and, by reason of the size of theorifice of the die, to adjust the amount of coating adhering to thestrand or yarn as it passes there beyond. The yarn, of course, isunwound from a conventional reel containing a continuous length of theyarn. After the first coating is applied to the yarn, it passesimmediately in continuous fashion through a falling stream of the secondcoating and thence to a wiping die. This wiping die also possesses anorifice to adjust the amount of the second coating onto the previouslycoated yarn. After passing through the second wiping die, the yarnproceeds laterally into a hot air oven which is maintained atatmospheric pressure. The temperature in the curing oven is maintainedat about 450 F. in order to effect fusion or gelation of the vinylplastisol. The oven is of a size to permit gelation considering thetemperature noted and the amount of resin which has been put onto theyarn. All of these factors are well known in the art and need not bedescribed or illustrated beyond the just preceding description, sincethe application of the principles and spirit of the present inventioncan be readily incorporated into these conventionally used operations bythose skilled in the art.

Polyester resins may also be used to form a polymerized resinous networkwithin the vinyl plastisol coating in place of epoxides of isocyanatogroup containing compounds. Polyester resins are, generally speaking,condensation products of polycarboxylic acids and polyhydric alcoholsand sometimes including fatty acid and/or fatty acid containing dryingoils. They are heat and catalyst convertible to an infusible mass.Catalysts for the polyester resin additive to the plastisol are of thefree radical type and include the peroxy catalysts, such as benzoyl andlauryl peroxide; organometals, such as triethyl aluminum, zincnapthenate, etc. and others Well known in the art. Since these are forthe most part solid materials, they are usually desirably includedtogether with the polyester in the vinyl plastisol and the coatingaccomplished in one step. Care must be exercised, however, to preventpremature catalysis and polymerization of the polyester prior to fusionof the plastisol in the curing oven. Liquid catalysts for polyesterresins, on the other hand, particularly if capable of boiling below 450F., can be use-d as a separate coating component permitting a greaterflexibility of operation, whereby the catalyst will migrate or difluseinto the polyester containing plastisol coating layer to polymerize thepolyester and yield a stronger, tougher coating.

It is frequently desirable to apply a size prior to the application ofthe catalyst or resinous additive (epoxide, isocyanato group containingcompound) containing plastisol. In such case, we prefer to utilize amore or less conventional starch or gelatin size but modified to containa very small amount of a Werner chromium complex, such asstearato-chromyl chloride and related water-soluble, coordinatedcompounds wherein the acido group has less than 10 carbon atoms. Thispre-sizing repels any water or moisture and prevents and/or reduces anytendency of the after-applied coatings being attacked at the interfaceof the glass fiber and said coating.

In accordance with another embodiment of the present invention, we applya first coating of a vinyl plastisol and resin onto a yarn composed ofglass fibers (using either a wiping die or by passing the yarn over arotating drum which picks up the coating from another drum partiallyimmersed in a tank of the coating) and thereafter the coated yarn ispassed through a special wiping die, which is essentially a hollowannular ring having spaced ports facing radially inward toward theorifice. This hollow annular ring is fluid-connected to a supply ofcatalyst for the resin and the connection includes a metering pump whichpermits the catalyst to be directed to the ports in any pre-selectedquantities depending upon the character of the resin used. The catalystis thus forced into the plastisol coating and together with the wipingaction of the die, e.g. the contact of the orifice with the plastisol,serves to vigorously mix the catalyst completely therethrough, wherebythe resin is polymerized rapidly and contemporaneously with fusion ofplastisol. The operation proceeds most efficiently, particularly where ahot catalyst is employed.

While there should be no limitation inferred from the followingtheoretical explanation, it is believed that the efiicacious resultsachieved by the present invention are obtained in the following manner.The additive resinous material, e.g. the epoxy group containing materialor the isocyanato adduct thereof or urethane, are intimately mixed withthe particles of vinyl chloride which are floating, as it were, in theplasticizer. Where the plasticizer content is relatively high, theparticles (particularly when the temperature is raised) commence toswell, bringing the particles into surface to surface contact. The lowboiling character of the preferred additive in accordance with thisinvention permits the additive to penetrate along with the plasticizerinto the actual particle. The catalysis thereof by the subsequentcoating containing the catalyst for the additive elTects cross linkingor polymerization to form, as it were, a reinforcing network chainwithin the vinyl chloride monomer as it continues to swell and fusesfinally in the heating step within the hot air oven. In the case of arather low plasticizer content vinyl plastisol, the vinyl chlorideparticle nonetheless swells to some degree and theadditive resin, e.g.the epoxy or the NCO or the NCO adduct or the urethane, surround theindividual particles floating in the plasticizer matrix. Then, as thesubsequently .ap plied catalyst (in the second coating) polymerizes theresinous phase, there is again formed a network or chain throughout thesimultaneously fused vinyl chloride plastisol layer furnishing areinforcement of the plastisol coating. It is further believed that thisnetwork, whether it be formed one way or the other as describedhereinabove, serves to provide a barrier against loss of plasticizerupon exposure to otherwise deleterious influences in the finalapplication. Thus, high temperature, sun, water, and general weatheringconditions, which would normally cause the plasticizer component toleach or become leached out of the coating, are prevented from so doingby the presence of the separate resinous phase which is of strongercharacter than the fused vinyl chloride polymer itself.

.There will now be described several preferred formulations and methodsfor carrying out the practice of the present invention in accordancewith the explanation given in detail hereinabove.

EXAMPLE I A mixture of vinyl chloride polymer plastisol and epoxideresin is prepared in accordance with the formulationof Table 1 below.

Table 1 Material: Weight, amt. in grams Vinyl chloride resin(Monsanto-Opalon 410) 1200 Mixture of phthalate and phosphatepasticizers 350 Aluminum paste colorant 12 Barium and cadmiumstabilizers 36 Hydrocarbon solvent diluent 89 Ethylene glycol diepoxide206 The foregoing ingredients were charged to a container and stirred toinsure a complete and intimate dispersion of the ingredients. It wasthen set aside for the moment and there was prepared a second mixture ofingredients according to the formulation of Table 2.

Table 2 Material: Weight, amt. in grams Vinyl chloride resin(Monsantopalon 410) 1200 Phthalate and phosphate plasticizers 200'Aluminum paste colorant 12 Di-N-dioctyl adipate 132 Filler 48 Stabilizer36 Epoxidized soybean oil 268 Diamyl propyl diethylene triamine 86 Theabove ingredients were mixed thoroughly and set aside for use in thepractice of the invention. Next, from an annular reel containing acontinuous supply of yarn of assembled and twisted glass fibers, therewas drawn in continuous fashion a strand of the glass fibers which waspassed through two wiping dies arranged in spaced-apart seriesrelationship and thence through a drying oven and finally to a wind-upreel. The openings in the respective wiping dies were adjusted so as toapply,

as determined by trial and error, an amount of a final coating onto theyarn such that it constituted 50% of the total weight of the driedcoated yarn. The coating of ingredients, set forth in Table 1 above, waspoured as a narrow stream onto the continuously traveling yarn. Themixture of ingredients,'set forth in Table 2, was applied subsequentlyat the second wiping die. The doubly coated yarn then passed into thedrying oven Where the temperature was maintained at 450 F. The yarnproceeding from the drying oven possessed a coating which was dry andstrong. It completely encapsulated the individual filaments making upthe yarn.

The mixtures, just described, possess a viscosity of about 4,000centipoises. The final composite coating was dry and tough to thefingernail. The coated yarn wove very nicely togive a screen which didnot soften at the point of the juncture of crossing coating yarns; thepoint of crossing was not flattened, although the crossing yarns werewell cohered together.

EXAMPLE II Mixtures of ingredients as described in the preceding examplewere prepared. The yarn was passed as described previously through twospaced-apart wiping dies in series and thence through a drying ovenmaintained at about 450 F. The mixtures, however, were applied inreverse order to that described in the previous example. That is, themixture according to the formulation in Table 2 was applied to the yarnfirst via the first wiping die, followed by the application of themixture according to the formulation in Table 1 through the secondwiping die. In this fashion the catalyst-containing coating was appliedfirst. This catalyst-containing coating polymerized and/ or linked thediepoxide as principally the outer layer of the two-layer assembly. Thiscreated a harder reinforced phase at the outer portion of the coatedstrand. The ultimately coated yarn was again found to be tough whenscratched with a fingernail; and was woven successfully into ascreen-type material. The crossing yarns of the woven material coheredwell together, yet did not flatten out, e.g. they retained theircircular crosssectional contour.

EXAMPLE III The procedure of the preceding example was repeated exceptthat prior to the application of the first coating (catalyst containing)through the wiping die, the yarn of assembled glass fibers is preheatedto a temperature of about 400 F. The remainder of the procedure wasexactly the same. This procedure, where the yarn is preheated, has theefiect of accelerating the diffusion of the amine catalyst componentthroughout the two coatings whereby the yarn can be drawn through thewiping dies or coating operation and the drying oven at a faster ratethan heretofore, e.g. 800 ft. per minute.

The normal speed at which the yarn travels is 450 ft. per minute.

EXAMPLE IV A plastisol coating was prepared in accordance with theformulation, set forth in Table 3.

Table 3 Material: Parts by weight Vinyl chloride (Monsanto-Opalon 410)10 Plasticizer 3.05 Epoxidized soybean oil 1.9 Colorant paste .6

Stabilizers .35 Hydrocarbon solvent diluent .7

The above ingredients were mixed by adding the vinyl chloride to thecontainer in which had been introduced the plasticizer components. Theother ingredients were added subsequently and stirred to produce asomewhat viscous sirup having a viscosity in the neighborhood of 5,000centipoises. This mixture was set aside while the following mixture wasprepared in accordance with the following formulation:

Table 4 Material: Parts by weight Vinyl chloride resin (Monsanto-Opalon410) 10 Plasticizer 4.95 Colorant paste .6 Stabilizers .35 Hydrocarbondiluent .7 Polyethylene glycol diamine .6

The above ingredients were mixed in the same manner as the justpreviously mentioned mixture. These mixtures were applied in turn to acontinuously moving yarn composed of glass filaments, passed betweenwiping dies to adjust the amount of coating adhering and thence passedthrough a drying oven maintained at 450 F. The double coated yarn wasthen wound up on a reel continuously. Examination revealed the yarn tobe uniformly coated and said coating to be tough when scratched with thefingernail. A similar procedure, but employing only the coating mixtureof Table 3 above, was found to yield a coated yarn which by comparisonwas softer and otherwise less desirable than the yarn bearing the twocoatings. The second coating (according to Table 4) containing thepolyethylene glycol diamine thus effectively cross linked the epoxygroups present in the epoxidized soybean oil component of the firstmixture making it tougher and harder. Furthermore, exposure of thedouble coated yarn to temperature and weathering conditions, which wouldnormally cause the coating to become more brittle, did not affect thedouble coated yarn in accordance with the present example.

EXAMPLE V The mixtures described in Example IV were applied in thisexample as coatings but in reverse order, namely, thecatalyst-containing mixture containing the polyethylene glycol diaminewas applied first, followed by the mixture containing the epoxidizedsoybean oil. The conditions were otherwise the same. The resultantcoated yarn was tough and scratch resistant. Close examination revealedit to constitute about 50% coating and 50% glass. The coated yarn waseasily woven into an open weave construction, yielding a very desirablescreening material. The point of juncture of the crossing yarns did notevidence any flattening. Rather, the yarns were circular in crosssection at the point of crossing, thereby having improved ultimatestrength.

EXAMPLE VI To illustrate the use of a urethane containing vinylplastisol there was prepared as a first mixture the ingredients, setforth in Table 5.

Table 5 Material: Parts by weight Vinyl chloride (Monsanto0palon 410)Mixture of plasticizers 4.95 Stabilizers 0.35 Colorant paste 0.2Antimony oxide Sb O 0.4 Hydrocarbon solvent diluent 0.5 Urethane adduct0.80

The above identified urethane adduct is a reaction product of tolylenediisocyanate, polyester and phenol. The above ingredients are mixed inthe usual fashion, adding the urethane adduct near the end. The mixturehas a viscosity in the neighborhood of 3,000 centipoises and is easilyapplied to a continuously moving yarn of glass fibers in the usualfashion. As a second coating there is applied a somewhat viscous alcoholsolution of diamino propyl diethylene triamine. This solution wassomewhat thinner than the plastisol mixture given in the table justabove. However, it is applied conveniently and in the passage of thecoated yarn through the drying oven, maintained at 425 F., the aminecatalyst difluses or permeates the first vinyl plastisol coating andeffectively initiates cross linking of the urethane adduct, yielding anultimately coated yarn which is tougher and more weather resistant thanheretofore conventional yarns coated with vinyl plastisol alone.

In accordance with another aspect of the present invention, it isdesired to apply a reflective and conductive metallic coating on aplastic coated yarn in order to provide tarnish resistance and, inaddition, yield a yarn which is extremely eye pleasing due to thereflective coating and is capable of transmitting heat and/ orelectricity for many applications where such properties would beadvantageous. To accomplish the foregoing most expeditiously, there isprepared a plastic coating mixture such as a vinyl plastisol in a mannerwell known in the art. To this there is added a reducing agentcompatible with the vinyl plastisol. Examples are: hydrazine, thehydrides of lithiurn, sodium, potassium, etc., the hydrosulfite salts ofthese same metals,.and other strong reducing agents. The so formedliquid reducing-agent-containing coating is applied to the yarn of glassfibers by passing it through a bath thereof or about a pick-up drum.Next, the coated yarn is passed through another bath or in contact witha pick-up drum where a solution of a silver, copper or gold salt isapplied to the previouslycoated yarn. Typical salts include nitrates,sulfates, chlorides, phosphates, carbonates, sulfonates, and the like.As indicated, the salts of silver, copper and gold are preferred;however, other salts of metals above hydrogen in the ElectromotiveSeries of metals are useful. These include arsenic, antimony, bismuth,mercury and platinum.

While we have disclosed, hereinabove, certain preferred modes ofperforming our invention, we do not thereby desire or intend to limitourselves solely thereto; furthermore, the proportions of the materialsutilized may be varied and equivalent chemical materials may beemployed, if desired, without departing from the spirit and scope of theinvention as defined in the appended claims.

We claim:

1. The method of coating a glass fiber yarn as to adapt it for use as aperforate screen defining element, said method comprising; (1) applyingto the yarn a coating comprising a low boiling substance capable ofcatalyzing polymerization of a material selected from the groupconsisting of an epoxy containing substance and an isocyanato groupcontaining substance, said substance having a boiling point above roomtemperature but not greater than 450 F. (2) applying a second coating ofa flowable composition comprising an intimate physical mixture of afusible vinyl plastisol and a polymerizable material selected from thegroup consisting of epoxy containing substances and an isocyanato groupcontaining substance and (3) exposing said coated yarn to a temperaturesuflicient to cause said substance to mignate into said second coatinglayer and polymerize said polymerizable material and suflicient tosimultaneously fuse said plastisol whereby the presence of saidpolymerized material reduces plasticizer loss normally associated withexposure of the coated yarn to elevated temperature and weatherconditions.

2. The method of coating a glass fiber yarn as to adapt it for use as aperforate screen defining element, said method comprising: (1) applyingto the yarn a coating comprising a relatively low boiling substancecapable of catalyzing polymerization of an epoxy containing substance,said substance having a boiling point above room temperature but notgreater than 450 F. (2) applying a second coating of a flowablecomposition comprising an intimate physical mixture of a fusible vinylplastisol and an epoxy containing substance and (3) exposing said coatedstrand to a temperature of from 300 F, to 450 F. to cause said lowboiling substance to migrate into said second coating layer andpolymerize said epoxy and sufficient to simultaneously fuse saidplastisol, whereby the presence of said polymerized material reducesplasticizer loss normally associated with exposure of the coated yarn toelevated temperature and weather conditions.

3. The method of coating a glass fiber yarn as to adapt it for use as aperforate screen defining element, said method comprising: (1) applyingto the yarn a coating of a relatively low "boiling substance capable ofcatalyzing polymerization of an isocyanato group containing substance,said substance having a boiling point above room temperature but notgreater than 450 F. (2) applying a second coating of a flowablecomposition comprising an intimate physical mixture of a fusible vinylplastisol and an isocyanato group containing substance and (3) exposingsaid coated strand to a temperatu e in the range of 300 F. to 450 F. tocause said low boiling substance to migrate into said second coatinglayer and elfect polymerization of said isocyanato group and sufficientto simultaneously fuse said plastisol, whereby the presence of saidpolymerized material reduces plasticizer loss normally associated withexposure of the coated yarn to elevated temperature and weatherconditions.

4. The method of coating a glass fiber yarn as to adapt it for use as aperforate screen defining element, said method comprising: (1) applyingto the yarn a coating of a liquid composition comprising an intimatephysical mixture of a fusible vinyl plastisol and a polymerizablematerial selected from the group consisting of epoxy containingsubstances and an isocyanato group containing substance (2) applying acoating of a relatively low boiling substance capable of catalyzingpolymerization of a material selected from the group consisting of epoxycontaining substances and an isocyanato group containing substance, saidlow boiling substance having a boiling point above room temperature butnot greater than 450 F. and (3) exposing said coated strand to atemperature causing said low boiling substance to migrate into s-aidfirst coating layer and polymerize said polymerizable material andsufiicient to simultaneously gel said plastisol to thereby yield astrand bearing a coating which is strong and resistant to weathering, byreason of the presence of the stronger polymerizate throughout the fusedvinyl plastisol coating.

5. The method of coating a yarn as claimed in claim 1 wherein the yarnis preheated prior to step 1.

6. The method as claimed in claim 4 wherein the coating of step 1possesses a viscosity of from 2,000 to 10,000 centipoises.

7. The method as claimed in claim 2 wherein the amount of catalyst isselected to be insufficient to cause polymerization of all of the epoxygroups whereby the resulting coated yarn is stabilized against heatdegradation.

8. The method as claimed in claim 1 wherein the coating of the firststep comprises in addition a vinyl plastisol component. I

9. The method as claimed in claim 1 wherein the substance of step 1 hasthe formula Y Si(OR) where R is a lower alkyl group, Y is an amine and aand b are positive numbers whose sum is 4.

References Cited by the Examiner UNITED STATES PATENTS 2,430,479 11/1947 Pratt et al. 2,657,151 10/1953 Gensel et al 11762.2 X 2,694,655l1/1954 Pullman et al. 117-126 2,814,834 12/1955 Hess et al. 2,819,2453/1957 Shorr 117-126 2,832,754 4/1958 Jex et al 117-126 2,843,560 7/1958Mika 117-126 2,862,281 12/1958 Klausner 117-54X 2,867,891 1/1959 Hortonet al 117-126 2,881,732 4/ 1959 Chrystman 117-126 2,885,419 5/1959Beinfest et al. 117-126 2,892,808 6/1959 Shafer 117-126 2,893,892 7/1959Pinte et al 117-72 2,929,737 3/ 1960 Tischbein 117-26 2,929,738 3/1960Bateson et a1 117-126 2,939,761 6/ 1960 Stein 117-126 2,974,062 3/ 1961Collier 117-76 3,067,059 12/1962 Iannarelli et al 117-126 3,083,1183/1963 Bridgeford 117-126 3,090,102 5/1963 Jannarelli 28-75 FOREIGNPATENTS 544,555 2/1956 Belgium.

625,992 8/1961 Canada. 1,212,187 3/1960 France. 1,025,302 2/ 1958Germany.

816,056 7/1959 Great Britain.

847,183 9/1960 Great Britain.

OTHER REFERENCES Sidlovsky, The Glass Industry, September 1960, pp.499-501 and 524.

Major Applications of Fiber Glass, The Glass Industry, June 1960, pp.341-344, 368, 369, 370 and 371 (page 370 relied on).

ALFRED L. LEAVITT, Primary Examiner.

RICHARD D. NEVIUS, JOSEPH REBOLD, JOSEPH B. SPENCER, P. H. KONDO, R. B.MURRAY, A. H. ROSENSTEIN, Assistant Examiners.

1. THE METHOD OF COATING A GLASS FIBER YARN AS TO ADAPT IT FOR USE AS APERFORATE SCREEN DEFINING ELEMENT, SAID METHOD COMPRISING: (1) APPLYINGTO THE YARN A COATING COMPRISING A LOW BOILING SUBSTANCE CAPABLE OFCATALYZING POLYMERIZATION OF A MATERIAL SELECTED FROM THE GROUPCONSISTING OF AN EPOXY CONTAINING SUBSTANCE AND AN ISOCYANATE GROUPCONTAINING SUBSTANCE, SAID SUBSTANCE HAVING A BOILING POINT ABOVE ROOMTEMPERATURE BUT NOT GREATER THAN 450*F. (2) APPLYING A SECOND COATING OFA FLOWABLE COMPOSITION COMPRISING AN INTIMATE PHYSICAL MIXTURE OF AFUSIBLE VINYL PLASTISOL AND A POLYMERIZABLE MATERIAL SELECTED FROM THEGROUP CONSISTING OF EPOXY CONTAINING SUBSTANCES AND AN ISOCYANATO GROUPCONTAINING SUBSTANCE AND (3) EXPOSING SAID COATED YARN TO A TEMPERATURESUFFICIENT TO CAUSE SAID SUBSTANCE TO MIGRATE INTO SAID SECOND COATINGLAYER AND POLYMERIZE SAID POLYMERIZABLE MATERIAL AND SUFFICIENT TOSIMULTANEOUSLY FUSE SAID PLASTISOL WHEREBY THE PRESENCE OF SAIDPOLYMERIZED MATERIAL REDUCES PLASTICIZERS LOSS NORMALLY ASSOCIATED WITHEXPOSURE OF THE COATED YARN TO ELEVATED TEMPERATURE AND WEATHERCONDITIONS.